Rt Classes For Profinet Io - Siemens SINAMICS S120 Series Function Manual

Communication via PROFINET IO

5.2 RT classes for PROFINET IO

5.2 RT classes for PROFINET IO
PROFINET IO is a scalable realtime communication system based on Ethernet technology.
The scalable approach is expressed with three realtime classes.
RT
RT communication is based on standard Ethernet. The data is transferred via prioritized
Ethernet telegrams. As standard Ethernet does not support any synchronization
mechanisms, isochronous operation is not possible with PROFINET IO with RT.
The real update cycle in which cyclic data is exchanged depends on the bus load, the
devices used and the quantity framework of the I/O data. The update cycle is a multiple of
the send cycle.
IRT
Two options are available with this RT class:
● IRT "high flexibility"
● IRT "high performance"
The real-time classes IRT "high flexibility" and IRT "high performance" can be selected as
options in the synchronization settings configuration area of HW Config. In the description
below, both these classes are simply referred to as "IRT".
Software preconditions for configuring IRT:
● STEP 7 5.4 SP4 (HW Config)
Note
For further information about configuring the PROFINET interface for the I/O controller and
I/O device, please refer to the following document: SIMOTION SCOUT Communication
System Manual.
IRT "high flexibility"
The telegrams are sent cyclically in a deterministic cycle (Isochronous Real Time). The
telegrams are exchanged in a bandwidth reserved by the hardware. One IRT time interval
and one standard Ethernet time interval are created for each cycle.
Note
IRT "high flexibility" cannot be used for isochronous applications.
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Function Manual, 12/2018, 6SL3097-5BD00-0BP0
Communication